First, here's how not to handle it: Don't organize everyone in the office so you all show up one day with clothespins on your noses. Three reasons: It hurts, it probably won't get the point across (the guy doesn't know he smells and won't connect the dots), and if he does figure it out he won't see the humor in it.

Second way to not handle it: Leaving a bar of soap on his desk with an attached, anonymous note. He'd be just as embarrassed as if someone had spoken with him. More so because he'll suspect everyone without ever finding out.

The right way to handle it: This is his manager's responsibility. If he reports to one of the five of you, that's the person who has to talk with him. The conversation should be matter-of-fact and businesslike. Sympathetic but not overly so, with no hinting, and with clarity about expectations. It should be brief, too. Since it will be a closed-door conversation, under the circumstances I doubt that will be a problem.

Example: "Don, there's an issue you need to address. It's a matter of personal hygiene. The fact of the matter is, you have a noticeable odor. It's strong enough that it makes the office a bit unpleasant to be in, and because of it your co-workers hesitate to work with you. You need to do something about it. Can I count on you to take care of the situation?"

Something his manager should be prepared for: There are medical conditions (hyperhidrosis and, at times, diabetes, to give two examples) that cause some people to exhibit offensive body odor even though their attention to personal hygiene is exemplary.

If the employee brings this up, the manager can insist that the employee seek medical assistance in dealing with the challenge and document the results. The manager must be discreet, no matter what social pressure the other employees apply ("Did you talk with him about it?" "Yes." "Well?" "The conversation was a private matter.") In the U.S., the conversation must be discreet for legal reasons -- HIPAA (Health Information Portability and Accountability Act) insists on it.

Without HIPAA, good manners would require it anyway.

Actually, the manager must be discreet no matter how the conversation goes. Even if "Don" explains to the manager that it's a medical situation, does everything he can, and specifically asks his manager to quietly explain his medical challenge to his co-workers. HIPAA (so does good sense) says no -- if Don wants his co-workers to know, he'll have to tell them.

If his manager isn't aware that there's an issue, one or more of you should make his manager aware. If his manager is aware and has decided to do nothing about it, I suppose the five of you can draw straws. Whoever gets the short straw has the conversation. You can do this, but it's dicey. All things considered, you're probably better off buying some air fresher units and living with the situation.

If you do decide to draw straws, the conversation should be similar to the one the manager would have, but not identical:

"Don, there's an issue I need to raise with you. The other ladies and I talked it over. We agreed someone needed to talk with you, and I was elected. The issue is that you have a noticeable odor. It's strong enough that it makes the whole office unpleasant. It isn't that we dislike you -- you seem like a nice enough sort. We don't want to embarrass you. It's serious enough that we decided we had to bring it up. Okay? Thanks."

If "Don" confides in you that this is the result of a medical situation, treat it as a private matter, just as if you were his manager. It's still up to him to inform everyone else if he wants them to know.

Good luck. If it's any comfort, you aren't the first. Not that knowing this makes the situation any easier.